1. Field of Invention
The present invention relates to an ink-jet head for forming an image by ejecting a small liquid drop of ink to a printing face.
2. Description of Related Art
A conventional ink-jet head is constructed wherein a plurality of pressure chambers are formed, and a nozzle is opened in correspondence with each of the pressure chambers and each nozzle is connected to one end of a corresponding one of the pressure
In the ink-jet head, ink from an ink supply source (for example, ink tank) is temporarily supplied to a common ink chamber and thereafter distributed from the common ink chamber to the pressure chambers. Further, by selectively applying pressure to each of the pressure chambers by an actuator, ink is ejected from the nozzle in correspondence with the pressure chambers to thereby form an image on a printing face.
The ink-jet head is generally formed by laminating and adhering a plurality of thin flat plates made of metal and the like. The pressure chambers and the common ink chamber are formed by etching the metal plates.
Here, an ink-jet head is also known in which a filter is provided at an ink supply passage connecting the common ink chamber and the ink tank (ink supply source) or an inkflow passage between the common ink chamber and each pressure chamber to thereby remove dust and dirt or impurities before reaching the pressure chamber or the nozzle such that the nozzle or the pressure chamber is not closed by dust and dirt.
Further, an ink-jet head is also publicly known in which a damper is provided at the common ink chamber and when pressure variation generated in a pressure chamber in ejecting ink is propagated to the common ink chamber, the pressure variation is absorbed by the damper to thereby prevent a phenomenon (cross talk) in which the pressure variation reaches other pressure chamber.
Further, an ink-jet head is also known in which a restriction flow passage having the configuration that a sectional area of the flow passage thereof is throttled is provided, to control the amount of ink supplied to the pressure chambers in ejecting ink, so as to prevent an excess amount of ink from being ejected.
Here, in recent years, by needs of high resolution formation of ink-jet recording, miniaturization and high integration of the ink-jet head structure have progressed. Therefore, it is highly requested to be able to simply fabricate an ink-jet head having the above-described filter located at the inside thereof. Further, when the above-described damper can simply be fabricated to include in an ink-jet head, fabricating steps can further be simplified, which is more preferable.
An object of the invention is to provide an ink-jet head having a filter and a damper (or a restriction flow passage and a filter) located at the inside thereof and capable of simplifying fabricating steps.
According to a first aspect of the invention, an ink-jet head comprises a plurality of nozzles that eject ink, a first flat plate layer including at least one flat plate formed with an array of pressure chambers each communicating with a corresponding one of the nozzles, a second flat plate layer including at least one flat plate formed with a common ink chamber having a shape elongated in a direction of the array of the pressure chambers, an ink flow passage that communicates at one end with a corresponding one of the pressure chambers and at an other end with the common ink chamber, an ink supply passage connecting the common ink chamber and an ink supply source, a flat plate member in a shape of a thin film disposed between the first flat plate layer and the second flat plate layer, a filter formed at the flat plate member for filtering the ink, and a damper chamber formed by a flat plate fixed on the flat plate member on a side thereof opposed to the common ink chamber.
Thereby, the filter for filtering ink and the damper for absorbing pressure variation of the common ink chamber can be fabricated in the flat plate member and therefore, fabricating steps can be simplified.
According to a second aspect of the invention, an ink-jet head comprises a plurality of nozzles that eject ink, a first flat plate layer including at least one flat plate formed with an array of pressure chambers each communicating with a corresponding one of the nozzles, a second flat plate layer including at least one flat plate formed with a common ink chamber having a shape elongated in a direction of the array of the pressure chambers, an ink supply passage connecting the common ink chamber and the ink supply source, a flat plate member disposed between the first flat plate layer and the second flat plate layer, and a restriction flow passage formed at the flat plate member for communicating one end thereof to the pressure chamber, communicating the other end thereof to the common ink chamber and controlling a flow of ink between the pressure chamber and the common ink chamber, and a filter formed at the inside of the restriction flow passage.
Thereby, the restriction flow passage for controlling an amount of ink supplied to the pressure chamber and the filter disposed at the inside of the restriction flow passage for filtering ink can be fabricated in the flat plate member and therefore, fabricating steps can be simplified. Further, a compact constitution of the flow passage can be realized to thereby facilitate highly integrated formation of the flow passage, which is adaptive to compact formation and high resolution formation of the ink-jet head.